Method of threading cable through conduit



Nov. 10, 1964 G. c. ENSLEY 3,156,449

METHOD OF THREADING CABLE THROUGH CONDUIT Filed Dec. 31, 1962 INVENTOR.Glover C. Ens/ey mum ATTORNEYS United States Patent 3,156,449 METHOD OFTHREADING CABLE THROUGH CONDUIT Glover C. Ensley, 525 N. Woodland Drive,North Kansas City, Mo. Filed Dec. 31, 1962, Ser. No. 248,800 2 Claims.(Cl. 254-1343) This invention relates to a device and method for pullingelectrical conductors and the like through protective conduits or tubesduring electrical construction jobs.

The principal objects of the present invention are: to provide a deviceand method whereby pulling force may be easily increased overconventional devices and methods for drawing electrical cable throughconduits; to provide such a device and method for threading electricalcables through conduits wherein one man may exert a pull heretoforeobtainable only by using at least two men or with auxiliary power drivenapparatus; to provide such a device and method which takes advantage ofa sheave or pulley to double the pulling force exerted on the electricalcable in the conduit; to provide such a sheave which is adapted to slidelongitudinally through the conduit without catching or jamming thereinand which is easily disassembled for threading the pull ropetherethrough intermediate the ends of the pull rope; and to provide sucha device and method which is simple and inexpensive to use and producessubstantial cost savings in both new construction and the alteration ofexisting construction.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings wherein are set forth by way of illustration and examplecertain embodiments of this invention.

FIG. 1 is a perspective view of a conduit sheave embodying thisinvention.

FIG. 2 is an exploded perspective view showing the sheave of FIG. 1disassembled for receiving the loop of a pull rope.

FIG. 3 is a cross-sectional view taken on the line 33 of FIG. 1 showingthe cooperating structure for maintaining the sheave parts in assembledrelation but easily disassembled.

FIG. 4 is a fragmentary cross-sectional schematic View of an electricalconduit illustrating a conventional electricians snake being used forthreading a doubled pull rope therethrough.

FIG. 5 is a fragmentary cross-sectional schematic View of the conduitillustrating the sheave cooperating with the pull rope for threading orpulling electrical cable therethrough with a 2-to-1 mechanicaladvantage.

Referring to the drawings, in more detail:

The reference numeral 1 generally indicates a conduit sheave embodyingthis invention. The sheave 1 has a body 2 with the rear end 3 thereofformed into an inwardly tapering conical section 4 and having an anchoreyelet 5 secured longitudinally thereto. The body 2, in the illustratedexample, is generally cylindrical in shape and is divided or bifurcatedinto a pair of laterally spaced parallel legs 6 and 7. The spacingbetween the legs 6 and 7 forms a notch or opening 8 into which isreceived a pulley roller 9. The legs 6 and 7 terminate at the outer ends10 thereof in rounded corners and curved configuration, the purposewhich will be explained hereinafter, defining the forward end 11 of thebody 2.

The pulley roller 9 is rotatably mounted between the legs 6 and 7 bymeans of a pin axle 12 having a square head 13 at one end thereofadapted to be received in a square recess 14 extending into the leg 7 toprevent pin rotation. Aligned bores 15 and 16 extend through therespective legs 6 and 7 for receiving the pin axle 12. The other end ofthe pin axle 12 has an annular recess 17 extending therearoundsupporting a split ring 18 which normally has an outside diameterslightly greater than the diameter of the bores 15 and 16. The ring 18,however, is resilient and radial compression thereon urges the ring toan outside dimension equal to the bores 15 and 16 whereby the pin axle12 may be inserted through the bores 15 and 16 with hand pressure.

The leg 6 includes a counterbore or recess 19 extending thereinto andforming a shoulder 20 past which the ring 18 may expand to theuncompressed dimension thereof for selectively locking the pin axle 12in position between the legs 6 and 7. It is to be understood that a rapby a hammer or concentrated thumb pressure will be sufficient to axiallydislodge the pin axle 12 for selectively removing same which releasesthe pulley roller 9 from between the legs 6 and 7 as illustrated in FIG.2.

In using the above described sheave, a conventional electricians tape 21is threaded through an electrical cable conduit 22 using a suitableguide 23 in the usual manner. A rope 24 is formed into a loop at 25intermediate the ends thereof and the loop 25 is secured in any suitablemanner to the guide 23 for drawing the rope 24 in doubled conditionthrough the conduit 22, FIG. 4. The loop 25 is pulled through theconduit 22 until it arrives at the cable input end 26 thereof. Thesheave 1 is then disassembled as illustrated in FIG. 2 and the loop 25is placed around the roller 9 whereupon the roller is reassembledbetween the legs 6 and 7.

An electric cable grip 27 of any suitable design is then secured to theend of the cable 28 to be pulled through the conduit 22. The grip 27 issuitably secured at 29 to the sheave eyelet 5. One end 30 of the rope 24is anchored or tied to any suitable fixed member 31 and the other orfree end portion 32 of the rope is pulled, in the illustrated example byhand at 33. The pulling force exerted on the rope at 32 is doubled atthe eyelet 5 due to the pulley advantage obtained and this substantiallydoubles the usual pulling power available for threading the cable 28through the conduit 22. During the rope pulling the rounded shapes onthe end 11 of the sheave body 2 travels in the direction of the conduitoutlet 34 and tends to cause the sheave to be deflected away from anyprotuberances or interruptions in the conduit 22 avoiding possiblejamming. Upon reaching the outlet 34, the sheave 1 is disassembled ifdesired for removal from the pull rope and the grip 27 is removed fromthe electrical cable 28 which is then available for splicing at theoutlet end 34 in the usual manner.

If desired, the sheave may be threaded through the conduit with the pullrope already engaged therewith, in which case the guide 23 will besecured to the eyelet 5 and the conical section 4 will reduce anytendency to jam.

It is to be understood that while certain forms of this invention havebeen illustrated and described it is not to be limited to the specificform or arrangement of parts and steps herein described and shows exceptinsofar as such limitations are included in the claims.

What I claim and desire to secure by Letters Patent is:

1. A method of pulling electrical cable through a conduit which includesthe steps of:

(a) doubling a pull rope and threading same through the conduit,

(b) engaging said rope in a pulley sheave,

(c) securing said sheave to said cable,

(d) anchoring one end of said rope, and exerting a pull on a free end ofsaid rope for drawing said sheave through said conduit with an increasedmechanical advantage.

2. A method of pulling electrical cable through a conduit comprising:

(a) forming a loop intermediate the ends of a pull rope,

(b) threading said rope loop through said conduit from the cable outletend thereof to the cable inlet end thereof with the rope ends remainingat said cable outlet end,

(c) engaging said loop at said inlet end in a pulley sheave,

(d) securing the cable to said sheave,

(e) anchoring one end of said rope at said outlet end, and exerting apull on the free end of said rope for drawing said sheave through saidconduit with an increased mechanical advantage.

References Cited in the file of this patent UNITED STATES PATENTS103,587 Eastman May 31, 1877 192,881 Scoville July 10, 1877 371,965Munsie Oct. 25, 1887 2,532,504 Tapsley Dec. 5, 1950

1. A METHOD OF PULLING ELECTRICAL CABLE THROUGH A CONDUIT WHICH INCLUDESTHE STEPS OF: (A) DOUBLING A PULL ROPE AND THREADING SAME THROUGH THECONDUIT, (B) ENGAGING SAID ROPE IN A PULLEY SHEAVE, (C) SECURING SAIDSHEAVE TO SAID CABLE, (D) ANCHORING ONE END OF SAID ROPE, AND EXERTING APULL ON A FREE END OF SAID ROPE FOR DRAWING SAID SHEAVE THROUGH SAIDCONDUIT WITH AN INCREASED MECHANICAL ADVANTAGE.